Design of 8-bit 250MHz sample-hold circuit

A 0.35 um BiCMOS dual-path, dual-differential sample-and-hold circuit is presented in this paper. The resolution of the circuit reaches 8 bits, and the sampling rate reaches 250 MSPS. The circuit features an alternate working mode, and reduces the circuit¿ demand for speed. From simulation of the circuit, it can be found that SNR is 55.8 dB, that INL and DNL are smaller than that of 8-bit ADC, which is ±0.2 LSB, and that the power current is 28 mA if the sampling rate is 250 MSPS at an input signal of 1 Vp-p with power supply of 3.3 V. The sample test results are as follows. SNR is 47.6 dB. INL and DNL are lower than that of 8 bit ADC, which is ±0.8 LSB.