30-100-MHz NPN-only variable-gain class-AB instantaneous companding filters for 1.2-V applications

Two variations of a continuous-time instantaneous companding filter were integrated in a 25 GHz bipolar process. Their -3-dB frequencies are tunable in the ranges of 1-30 and 30-100 MHz. The DC gains are controllable up to 10 dB. The measured dynamic ranges for a 1% total harmonic distortion are 62.5 and 50 dB, for the 30 and 100 MHz filters, respectively. At maximum cutoff frequencies, the filters dissipate 6.5 mW from a 1.2 V supply.

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