High-Speed GaAs 1/8 Dynamic Frequency Divider Stabilized for Supply Voltage Fluctuation and its Phase Noise Characteristics

A new GaAs 9.6 GHz 1/8 dynamic frequency divider with 1 ¿m long gate FETs has been developed. This divider is consists of a 1/2 dynamic divider for the first stage, and 1/4 static dividers for subsequent stages. This dynamic divider has a double loop structure using a pair of differential amplifiers for high speed and stable operation with supply voltage fluctuations of ± 0.5 V around -7 V. Since GaAs FETs have a higher 1/f noise than Si transistors, higher phase noise occurs in phase-locked oscillators (PLO) using GaAs frequency dividers. However, no quantitative comparison has been reported. The measured phase noise characteristic of a 6.4 GHz PLO is -92 dBc/Hz at 1 kHz off-carrier frequency and is comparable to that of a Si divider. This satisfies the requirements for most microwave PLOs.