Experimental Verification of On-Chip Biquadratic Filter and Oscillator

This article presents an improved gain-independent tunable voltage-mode (VM) multifunction biquadratic filter (MBF) based on the current-feedback amplifier (CFA), which is easily modified as a quadrature oscillator (QO). Each of the proposed VM-MBF and VM-QO configurations is implemented on a chip employing Taiwan Semiconductor Manufacturing Company (TSMC)
$0.18~\mu \text{m}$
process with three CFAs, two grounded capacitors, and five resistors. The proposed VM-MBF and VM-QO configurations are both implemented on integrated circuits (ICs) with chip areas of 0.24 and 0.23 mm2 (without PADs), respectively. Based on a ±0.9 V voltage supply and a rail-to-rail input voltage range of 0.05
$\text{V}_{\text {pp}} \le {V}_{\text {in}} \le {1.5}~\text{V}_{\text {pp}}$
, the VM-MBF chip has a maximum efficiency of 83.33%. For linear evaluation of the VM-MBF chip, the measured input 1-dB compression point (P1dB) is about 8.1 dBm. For nonlinear evaluation of the two-tone test, the measured third-order intercept point (TOI) and third-order intermodulation distortion (IMD3) are about 27.26 dBm and −67.5 dBc, respectively. The measured phase noise (PN) of the VM-MBF chip is −101.06 dBc/Hz at 1 kHz offset. With high-input (HI) and low-output (LO) impedances, the proposed VM-MBF can simultaneously achieve inverting low-pass (ILP), inverting bandpass (IBP), and non-inverting band-stop (NBS) responses with gain-independent controllability. It can be easily modified into a VM-QO with fully decoupled control of both the frequency of oscillation (FO) and condition of oscillation (CO). The simulation and measurement results in the time and frequency domains confirm the theories of the proposed VM-MBF and VM-QO configurations.