Microchip Technology U2793B-MFS

Overview

U2793B-MFS from Atmel is a 300-MHz quadrature modulator IC designed for digital radio up-conversion, featuring single-ended 50-Ω RF/LO ports, 90° phase-control loop, duty-cycle regeneration, and low-power 15 mA operation at 5 V. It supports LO frequencies from 30 MHz to 300 MHz and delivers ≥45 dB LO suppression and ≥45 dB sideband suppression in GSM, PCN, JDC, and WLAN transmitters.

For engineers reviewing the U2793B-MFS datasheet, U2793B-MFS pinout, U2793B-MFS application, or U2793B-MFS equivalent, key selection considerations include its adjustment-free I/Q modulation architecture, spurious performance tunability via LP1/LP2 pins, power-down mode, and compatibility with Atmel's U2795B mixer for up-conversion to 2 GHz.

Technical Context

The U2793B-MFS integrates a frequency doubler, duty-cycle regenerator, and precision 90° control loop to generate orthogonal I/Q signals without external calibration. Its baseband inputs accept differential 0–50 MHz signals (1.0 Vpp typ.), while the LO path accepts -15 dBm single-ended input across 30–300 MHz with 50 Ω impedance (50 Ω + 15 pF).

It operates from 4.5–5.5 V over -40°C to +85°C ambient, uses an internal 2.5 V reference (±50 mV tolerance), and achieves <1° phase error and <±0.25 dB amplitude error - enabling high-fidelity QAM and π/4-DQPSK modulation in burst-mode digital radios.

Key Specifications

Pinout & Package

U2793B-MFS is housed in a 20-pin SSO20 (Shrink Small Outline) package with exposed thermal pad, optimized for RF signal integrity and thermal dissipation in compact radio modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quadrature modulator applications.

Compared with U2793B-MFS, ADL5375-05 offers broader RF bandwidth but demands more board space and external LO conditioning, while TRF3705 reduces bill-of-materials with on-chip synthesis yet sacrifices fine-grained spurious control and low-current advantage.

Availability

U2793B-MFS is available at Aetrix Electronics and suitable for GSM transmitter modules, WLAN up-converter designs, PCN/JDC handsets, and DECT cordless phone systems requiring stable component supply, long-lifecycle assurance, and traceable sourcing.

Supply support for U2793B-MFS 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

Atmel Corporation (now part of Microchip Technology) is a semiconductor company specializing in microcontrollers, RF ICs, and mixed-signal solutions for communications and embedded systems.

The U2793B-MFS belongs to Atmel's UHF RF modulator product line, engineered specifically for low-power, adjustment-free digital radio transmitters operating in 30–300 MHz LO bands.

FAQ

What is the recommended LO input level for U2793B-MFS across its full frequency range?

The U2793B-MFS requires -15 dBm LO input at 150 MHz, with level increasing to -5 dBm at 30 MHz and decreasing to -15 dBm at 300 MHz per Figure 6-4. The LO input impedance is 50 Ω in series with 15 pF, so matching networks must account for capacitive reactance. Operating outside the specified -15 to -5 dBm range risks degraded LO suppression or increased distortion in the U2793B-MFS output.

How does the duty-cycle regenerator in U2793B-MFS improve sideband suppression?

The duty-cycle regenerator inside U2793B-MFS reshapes the incoming LO waveform to precisely 50% duty cycle before feeding the quadrature generator, minimizing even-order harmonics that cause sideband asymmetry. This function enables ≥35 dB sideband suppression without external LO conditioning circuits, directly contributing to the U2793B-MFS's adjustment-free operation and reduced system-level filtering requirements.

Can U2793B-MFS be used with DC-coupled baseband inputs, and what biasing is required?

Yes, U2793B-MFS supports DC-coupled baseband inputs using the internal 2.5 V VREF (pin 13) as common-mode bias. Per Figure 8-2, resistive dividers (e.g., 10 kΩ each) set the DC offset at BBAI/BBBI pins to 2.5 V, ensuring optimal linearity and LO suppression. Input voltage range remains 1.0 Vpp differential, and mismatched DC bias degrades the U2793B-MFS's <±0.25 dB amplitude error specification.

What is the function of pins LP1 and LP2 on U2793B-MFS, and how are they configured?

Pins LP1 and LP2 on U2793B-MFS provide external tuning of low-pass filtering and output power control. Adding a chip capacitor (1–10 pF) between LP1 and LP2 improves spurious performance at low LO frequencies, while adding a parallel resistor adjusts output level to subsequent stages without degrading LO suppression or noise floor. This configuration preserves the U2793B-MFS's core performance while enabling application-specific optimization.

Does U2793B-MFS support power-down mode, and how is it activated?

Yes, U2793B-MFS supports power-down mode: driving PU (pin 1) ≤0.5 V reduces supply current to 1 µA, as specified in Section 5.1. This feature enables rapid on/off cycling in TDMA or burst-mode radios. The settling time from power-down to full operation is <10 µs (with 100 pF capacitor on SPU pin 8), allowing the U2793B-MFS to meet tight slot timing in GSM and PCN systems.