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Analog Devices Inc. LT5503EFE#PBF
- Part No.:
- LT5503EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- RF Modulators
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT5503EFE#PBF.pdf
- Description:
- RF MODULATOR 1.7-2.7GHZ 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,071
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Product details
Overview
LT5503EFE#PBF from Analog Devices (formerly Linear Technology) is a dual-function RF front-end IC integrating a direct IQ modulator and an independent double-balanced mixer for wireless transmitters. It operates with 1.2–2.7GHz modulator output, 1.7–2.7GHz mixer RF output, 120MHz baseband bandwidth, –3dBm P1dB at 2.45GHz, and 4-step digital VGA control. It is used in IEEE 802.11b WLAN, MMDS, and WLL transmitter designs.
For engineers reviewing the LT5503EFE#PBF datasheet, LT5503EFE#PBF pinout, LT5503EFE#PBF application, or LT5503EFE#PBF equivalent, key selection considerations include its integrated 90° phase shifter, LO2 ÷1/÷2 mode control, carrier- and image-suppression performance (–32dBc typical), supply voltage range (1.8–5.25V), and 20-lead TSSOP package with exposed ground pad.
Technical Context
The LT5503EFE#PBF implements a precision quadrature modulator with internal 90° phase shifter and variable gain amplifier (VGA), enabling direct baseband-to-RF conversion without external phase-matching components. Its modulator accepts differential I/Q inputs (BI±, BQ±) with 18kΩ input resistance and 0.8pF capacitance, internally biased to 1.4V for low-voltage operation.
The independent double-balanced mixer features two LO inputs: LO1 (1.4–2.4GHz) and LO2 (50–1000MHz), with DMODE pin selecting LO2 ÷2 (750MHz → 375MHz) or ÷1 (750MHz → 750MHz) operation. Mixer output (MX±) is differential open-collector, requiring external biasing and matching to generate 2.45GHz RF for the modulator's MODIN port.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Modulator RF Output Range | 1.2GHz to 2.7GHz - supports multi-band ISM and licensed band transmitters including 2.45GHz WLAN and 1.9GHz PCS. |
| P1dB Output Power | –3dBm at 2.45GHz - defines maximum linear output before compression; sets usable dynamic range for high-fidelity modulation. |
| Baseband Bandwidth | 120MHz - enables wideband modulation schemes such as OFDM and high-data-rate DSSS without signal roll-off. |
| Carrier Suppression | –32dBc typical - minimizes unwanted carrier feedthrough in zero-IF architectures, reducing DC offset sensitivity. |
| Image Suppression | –34dBc typical - ensures clean sideband generation critical for spectral mask compliance in FCC/ETSI-regulated systems. |
| VGA Gain Control Steps | 0dB / 4.5dB / 9dB / 13.5dB - digitally programmable attenuation via GC1/GC2 pins enables precise output power management across temperature and process variation. |
| Supply Voltage Range | 1.8V to 5.25V - allows direct integration into battery-powered (1.8V/3.3V) and line-powered (5V) RF subsystems without level-shifting. |
Pinout & Package
LT5503EFE#PBF is housed in a 20-lead plastic TSSOP (FE package) with exposed thermal pad (Pin 21) that must be soldered to PCB ground for thermal and electrical integrity. Package dimensions: 6.5mm × 4.4mm × 1.1mm, pitch 0.65mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BQ– / BQ+ (1,2) | Q-channel differential baseband input | Internally biased to 1.4V; accepts ±1VP-P differential swing; 18kΩ input resistance enables direct DAC coupling. |
| GC1 / GC2 (3,18) | Digital VGA gain control inputs | Two-bit logic selects 4 attenuation states (0/4.5/9/13.5dB); draws ≤2µA when high; TTL-compatible thresholds. |
| MODIN (4) | Modulator RF carrier input | Single-ended, AC-coupled, requires external 50Ω matching network; accepts –20 to –10dBm input power. |
| VCCMOD / VCCRF / VCCVGA / VCCLO1 / VCCLO2 (5,6,16,8,15) | Separated power domains | Independent supplies isolate modulator core, RF buffer, VGA, LO1, and LO2 circuits to minimize crosstalk and optimize noise performance. |
| LO1 / LO2 (7,14) | Mixer local oscillator inputs | LO1: 1.4–2.4GHz, AC-coupled, matched to 50Ω; LO2: 50–1000MHz, internally matched, AC-coupling required. |
| MX+ / MX– (10,11) | Differential mixer RF output | Open-collector outputs requiring external bias choke and balun; deliver –12.7dBm typical at 2.45GHz in ÷2 mode. |
| MODOUT (17) | Modulator RF output | Single-ended, open-collector; requires VCC bias choke and external matching to 50Ω; delivers –3dBm P1dB at 2.45GHz. |
| MODEN / MIXEN (13,12) | Enable controls | CMOS-compatible enable pins with <1µs switching; reduce supply current to 50µA (modulator) or 10µA (mixer) in shutdown. |
| DMODE (9) | LO2 divider mode select | Low = LO2 ÷2 (e.g., 750MHz → 375MHz), High = LO2 ÷1 (750MHz → 750MHz); enables flexible dual-conversion LO planning. |
| BI– / BI+ (20,19) | I-channel differential baseband input | Functionally identical to BQ±; 120MHz bandwidth and 1.4V internal bias support high-fidelity I/Q signal integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 90° quadrature phase shifter | Eliminates need for external polyphase filters or transformer-based IQ splitting, reducing BOM count and layout sensitivity. |
| Independent double-balanced mixer | Enables flexible dual-conversion architecture: LO1 + LO2 mixing generates modulator carrier (e.g., 2075MHz + 750MHz → 2450MHz), decoupling LO design from modulator path. |
| 120MHz baseband modulation bandwidth | Supports 20MHz-wide IEEE 802.11b channels and higher-order QAM without group delay distortion or amplitude droop. |
| 4-step digital VGA with 13.5dB range | Provides coarse output power control without analog control voltage drift or DAC dependency; compatible with simple GPIO interfaces. |
| Separate power domains per functional block | Reduces inter-block noise coupling-e.g., LO2 switching noise does not modulate modulator bias rails-improving EVM and adjacent channel leakage. |
| Exposed thermal pad (Pin 21) | Enables efficient heat dissipation (θJA = 38°C/W) and stable RF performance under continuous transmit duty cycles in compact handheld modules. |
Applications
| IEEE 802.11b WLAN Transmitter | MMDS Fixed Wireless Transmitter |
|---|---|
Use Scenario: 2.4GHz ISM-band Wi-Fi access point transmitting DSSS/CCK-modulated data at 11Mbps. IC Role / Device Role / Timing Role: Direct IQ modulator converts baseband I/Q signals to 2.45GHz RF; mixer optionally generates carrier from dual-LO architecture. Use Value: Integrated 90° shifter and 120MHz bandwidth ensure <–35dB EVM at 11Mbps; –32dBc carrier suppression meets FCC spectral mask requirements. | Use Scenario: 2.5–2.7GHz broadband wireless local loop (WLL) base station uplink transmitter serving multiple CPE units. IC Role / Device Role / Timing Role: Modulator handles wideband QPSK/16-QAM uplink signals; mixer provides flexible LO synthesis for frequency-agile channel allocation. Use Value: 4-step VGA enables precise per-CPE power control; –34dBc image suppression maintains ACLR >45dB in dense multi-user deployments. |
| PCS Wireless Data Transmitter | Wireless Local Loop (WLL) Terminal |
Use Scenario: 1.9GHz PCS band mobile data terminal using π/4-DQPSK for voice/data convergence. IC Role / Device Role / Timing Role: LT5503EFE#PBF serves as single-chip RF front-end, accepting baseband I/Q from DSP and delivering modulated RF to PA driver. Use Value: 1.8V minimum supply enables direct connection to Li-ion battery rail; 13.5dB VGA range accommodates varying PA gain profiles across production lots. | Use Scenario: Outdoor subscriber unit in 2.5GHz WLL system operating in –40°C to +85°C ambient with strict MTBF requirements. IC Role / Device Role / Timing Role: Modulator processes TDMA burst signals; mixer provides robust LO2 ÷2 operation for stable 375MHz IF generation in temperature-varying environments. Use Value: Guaranteed –40°C to +85°C operation with <±1dB gain variation; exposed pad ensures thermal reliability over 10-year field life. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar RF modulator/mixer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADL5375-05ACPZ-R7 | Higher frequency range (300MHz–6GHz), integrated LO buffer, no on-chip mixer; requires external LO source. | Best suited for single-conversion architectures where LO is generated off-chip; lacks dual-LO mixer functionality of LT5503EFE#PBF. | Select ADL5375-05 when wider frequency coverage and higher output power (+6dBm P1dB) are prioritized over integrated mixer flexibility. |
| TRF3705IRGZT | Integrated PLL/VCO, 0.4–4.2GHz operation, lower baseband bandwidth (60MHz), no separate mixer section. | Targets highly integrated transceivers with on-chip frequency synthesis; unsuitable for dual-conversion systems requiring independent LO mixing. | Choose TRF3705IRGZT for simplified RF BOM in cost-sensitive, single-LO applications where 60MHz bandwidth suffices. |
Compared with ADL5375-05ACPZ-R7 and TRF3705IRGZT, the LT5503EFE#PBF uniquely combines a wideband IQ modulator with a fully independent double-balanced mixer in one die-enabling dual-conversion transmitter topologies without external mixers or complex LO routing, while maintaining low-voltage operation and high modulation accuracy.
Availability
LT5503EFE#PBF is available at Aetrix Electronics and suitable for IEEE 802.11b WLAN, MMDS fixed wireless, and PCS wireless data applications requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant lead-free packaging.
Supply support for LT5503EFE#PBF includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Analog Devices, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and RF ICs, formed through the acquisition of Linear Technology in 2017.
The LT5503EFE#PBF belongs to ADI's legacy Linear Technology RF front-end product line, designed specifically for low-voltage, high-accuracy digital modulation in wireless infrastructure and terminal equipment.
FAQ
What is the operating frequency range of the LT5503EFE#PBF modulator output?
The LT5503EFE#PBF modulator delivers RF output from 1.2GHz to 2.7GHz. This range covers key ISM bands (2.4–2.5GHz), PCS (1.85–1.99GHz), and MMDS (2.5–2.7GHz). Performance is characterized at 1.2GHz, 1.9GHz, and 2.4GHz with external matching networks optimized per band. The LT5503EFE#PBF maintains ≥–32dBc carrier suppression and ≥–34dBc image rejection across this full span.
How does the LT5503EFE#PBF handle baseband input biasing?
The LT5503EFE#PBF internally biases all four baseband inputs (BI+, BI–, BQ+, BQ–) to 1.4V, optimizing input voltage swing at low supply voltages (1.8V–5.25V). This bias remains stable over temperature and varies by only ~50mV across the full supply range. External DC bias can override the internal reference, provided it stays between 1.4V and VCC – 0.4V. The LT5503EFE#PBF supports both AC-coupled (capacitor-coupled) and DC-coupled (DAC-driven) interfaces without external resistive networks.
What is the function of the DMODE pin on the LT5503EFE#PBF?
The DMODE pin on the LT5503EFE#PBF controls the division ratio of the LO2 input to the internal mixer: logic low selects divide-by-2 (e.g., 750MHz → 375MHz), and logic high selects divide-by-1 (750MHz → 750MHz). This enables flexible dual-conversion LO planning-such as generating a 2.45GHz modulator carrier from 2075MHz (LO1) and 750MHz (LO2) inputs-and simplifies frequency planning in multi-band transmitters. The LT5503EFE#PBF specifies LO2 operation from 50MHz to 1000MHz in either mode.
Can the mixer and modulator sections of the LT5503EFE#PBF operate independently?
Yes, the mixer and modulator sections of the LT5503EFE#PBF are functionally independent and can be used separately. The modulator can accept an externally generated carrier on MODIN, while the mixer's MX± outputs can drive other circuitry (e.g., a second modulator or filter stage). Independent enable pins (MODEN and MIXEN) allow power gating of each section. When unused, the mixer may be disabled to reduce current draw (to 10µA), preserving the LT5503EFE#PBF's suitability for battery-operated devices.
What package type and thermal requirements apply to the LT5503EFE#PBF?
The LT5503EFE#PBF uses a 20-lead plastic TSSOP (FE package) with an exposed thermal pad (Pin 21) that must be soldered to the PCB ground plane. This pad is essential for thermal management (θJA = 38°C/W) and RF grounding. The LT5503EFE#PBF operates from –40°C to +85°C and requires proper decoupling: 1000pF + 0.1µF capacitors on each VCC pin, and a 2pF high-frequency capacitor near VCCVGA (Pin 16). Failure to solder the exposed pad degrades RF performance and risks thermal overstress.
LT5503EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Modulator/Mixer
- LO Frequency:
- 1.4GHz ~ 2.4GHz
- RF Frequency:
- 1.7GHz ~ 2.7GHz
- P1dB:
- -15dBm
- Noise Floor:
- -152dBm/Hz
- Output Power:
- 12.7dBm
- Current - Supply:
- 38 mA
- Voltage - Supply:
- 1.8V ~ 5.25V
- Test Frequency:
- 2.4GHz
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT5503EFE#PBF FAQ
1.How can I place an order for LT5503EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT5503EFE#PBF on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LT5503EFE#PBF reliable?
The price and inventory of LT5503EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT5503EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT5503EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT5503EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT5503EFE#PBF?
LT5503EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT5503EFE#PBF order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LT5503EFE#PBF?
For technical support, including LT5503EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT5503EFE#PBF requirements.
6.How does Aetrix verify that LT5503EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT5503EFE#PBF products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LT5503EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT5503EFE#PBF?
All LT5503EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT5503EFE#PBF, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LT5503EFE#PBF part is unused and in its original packaging.
Return procedure for LT5503EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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