The Architectures of the Differential Amplifiers on SiGe Bipolar Transistors with Low Voltage Supply

The architectural solutions of the differential stages (DS) on the bipolar SiGe transistors of microwave range operating at low voltage supply are suggested. The peculiarity of the reviewed circuits lies in the absence of the traditional current references in the common emitter loop of DS which is changed by comparatively low-ohmic resistor (R₀). The special channels of compensation of the effect of R₀ at the coefficient of the input common-mode rejection ratio (K_CMRR) are fed into the circuits of such DS to increase K_CMRR. The results of the simulation and layout of the circuit of OA of microwave range according to SiGe process are given. The UGB of OA on the single-ended output is 8.7 GHz, whereas its differential value is 17.4 GHz with the phase margin PM=67°. The coefficient of the common-mode rejection for the differential output is 80 dB.