A 100 MHz IF amplifier quadrature demodulator for GSM cellular radio mobile terminals

Abstract

A circuit including a 100 MHr IF amplifier with a digitally controlled gain of 0-to-45 dB, a quadrature phase-shifter, balanced mixers, and activelsleep mode capability is described. The measured gain and quadrature phase variation was less than 1 dB and lorespectively. The 92 mW circuit was fabricated using a 4.0 GHz complementary bipolar process.

A 2-V low-power CMOS direct-conversion quadrature modulator with integrated quadrature voltage-controlled oscillator and RF amplifier for GHz RF transmitter applications

“…For simplicity, the series connection of components is transformed into the equivalent parallel connection. The component values of the equivalent half circuit can be derived as (9) where is the frequency of the modulated signal at output nodes, , , and are the drain-substrate capacitances of the MOS transistors M25 M28, M33, and M35, respectively, , , and are the gate-drain capacitances of MOS transistors M33, M34, and M35, respectively, is the equivalent capacitance of junction varactors MD5 and MD6, is the input capacitance load of the output buffer including the parasitic capacitance of the metal connection lines, , , and are the output resistances of MOS transistors M25 M28, M33, and M35, respectively, and is the current bias in the MOS transistor M33.…”

“…So far, there have been four methods proposed to generate LO signals with quadrature phases [8]- [16]. They are: 1) Resistance-capacitance capacitance-resistance (RC-CR) phase shifter [8] and [9]; 2) frequency divider [10]; 3) even-stage ring oscillator [11]- [14]; and 4) two direct-coupled and cross-coupled inductance-capacitance ( )-load VCOs [15] and [16]. Among them, the -load VCO has low phase noise and stable oscillation frequency.…”

Highly integrated RF-IC's for GSM and DECT systems-A status review

“…1) single conversion to one IF of 40-130 MHz followed by a conversion to I/Q-Baseband [1], [2]; some years later IF frequencies between 250-450 MHz were introduced [3], [8]; 2) dual conversion with two IF-frequencies, followed by a subsampling A/D conversion; 3) dual conversion with two IF-frequencies, follwed by a phase comparator and a RSSI evalution; 4) homodyn concept with direct conversion to I/Q Baseband [13], [15]; 5) that direct A/D conversion or subsampling for low power application is still not in use and a dream of the future.…”

“…1). This designs were based on medium-level integration (partly building blocks) and used a 5-V supply voltage [1], [2]. The RF board design of a complete handheld at that time consists of about 400-500 components (Cs, Ls, R, IC's, etc.…”