Asahi Kasei Microdevices/AKM AK1575

Overview

AK1575 from Asahi Kasei is a highly integrated up-converter mixer with fractional-N frequency synthesizer and triple-band VCO, designed for microwave radio links and cellular base station transceivers. It supports IF input from 20 MHz to 1000 MHz, RF output from 690 MHz to 4000 MHz, and internal LO generation from 262.5 MHz to 4400 MHz, with typical conversion gain of –1.5 dB and IIP3 of +24 dBm at 2 GHz.

For engineers reviewing the AK1575 datasheet, AK1575 pinout, AK1575 application, or AK1575 equivalent, key selection considerations include its dual-supply operation (4.75–5.25 V for mixer, 2.7–3.6 V or 4.75–5.25 V for synthesizer/VCO), 32-pin QFN package with exposed thermal pad, serial 24-bit CPU interface, and configurable fast-lock mode with programmable charge pump current scaling.

Technical Context

The AK1575 integrates a high-linearity differential mixer core, a three-band VCO with automatic band calibration, and a fractional-N PLL using a 3rd-order ΣΔ modulator (AX modulator) for spurious suppression. Its phase-frequency detector operates up to 40 MHz, and normalized phase noise is –218 dBc/Hz.

Operation modes are controlled via PDN pin and register bits MODE[1:0], enabling six functional states - including standalone mixer, synthesizer-only, VCO+synthesizer output, and full up-conversion with local signal routing to external circuitry via open-collector LOP/LON pins.

Key Specifications

Pinout & Package

AK1575 is housed in a 32-pin QFN package (5 mm × 5 mm × 0.85 mm, 0.5 mm pitch) with an exposed thermal pad that must be connected to ground for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar up-converter mixer + synthesizer applications.

Compared with HMC6300LP5E and TRF372017, AK1575 uniquely combines sub-6 GHz up-conversion, integrated triple-band VCO, and fractional-N synthesis in a single 5 mm QFN - eliminating external LO sources and simplifying layout while maintaining –111 dBc/Hz phase noise and +24 dBm IIP3 for macro-cell BTS deployment.

Availability

AK1575 is available at Aetrix Electronics and suitable for microwave radio links, cellular base station transceivers, and repeater systems requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for AK1575 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

Asahi Kasei Microdevices Corporation (AKM) is a Japanese semiconductor company specializing in analog, mixed-signal, and RF ICs for communications, industrial, and consumer applications.

The AK1575 belongs to AKM's high-performance RF front-end product line, engineered specifically for wireless infrastructure where integration, linearity, and spectral purity are critical in compact form factors.

FAQ

What is the recommended power-up sequence for AK1575?

The AK1575 requires strict sequencing: first assert PDN = low while stabilizing all supplies (VDD1/VDD2/VDD3), wait ≥10 ms for VREF1 LDO stabilization, write all registers (0x01–0x04), then raise PDN to high. After PDN goes high, wait ≥500 µs for internal bias stabilization before writing Address 0x01 to trigger VCO calibration and PLL lock. This sequence prevents undefined register states and ensures reliable band selection.

How does the AK1575 achieve low phase noise despite wide VCO tuning range?

The AK1575 achieves –111 dBc/Hz phase noise at 100 kHz offset through its triple-band VCO architecture, which limits Kvco to ~0.02 MHz/V per band, and a high-performance fractional-N PLL with normalized phase noise of –218 dBc/Hz. Band calibration automatically selects the optimal VCO core for the target frequency, minimizing sensitivity-induced noise while maintaining 262.5–4400 MHz coverage - a key advantage over single-band VCO solutions.

Can AK1575 operate with an external LO instead of its internal VCO?

Yes, AK1575 supports external LO injection via LOP/LON pins when MODE[1:0] = 3. In this configuration, the internal VCO and synthesizer are disabled, and the device functions solely as a high-linearity up-converter. The mixer retains full IF/RF range (20–1000 MHz IF, 690–4000 MHz RF), and LO input level tolerance is specified at –10 to +10 dBm for differential drive, enabling interoperability with third-party synthesizers or signal generators.

What is the function of the MIXBIAS and CPBIAS pins on AK1575?

MIXBIAS and CPBIAS are precision current-setting terminals: MIXBIAS (typically 33 kΩ to GND) adjusts mixer bias current and thus conversion gain and noise figure, while CPBIAS (typically 27 kΩ to GND) scales the charge pump current (Icp) according to Icp = 8.1 µA × (CP1/CP2 setting + 1) / R. Both resistors directly impact linearity, power consumption, and PLL lock dynamics - making them critical for system-level optimization of AK1575 performance.

Does AK1575 support fast frequency hopping, and how is it implemented?

Yes, AK1575 supports fast frequency hopping via its Fast Lock mode. When FASTEN = 1 and FAST[3:0] is set (e.g., 0x0F = 8191 cycles), writing Address 0x01 triggers a temporary high-current charge pump state (CP2) for rapid VCO settling. Lock time is reduced to <100 µs - over 5× faster than normal mode - with automatic reversion to CP1 after the timer expires. This enables agile channel switching in TDD-LTE and dynamic spectrum access systems without firmware overhead.