Abstract
In this paper, a method of realizing voltage-mode (VM) non-inverting high-pass filter (HPF), band-pass filter (BPF), low-pass filter (LPF), and inverting low-pass filter (ILPF) transfer functions structure with two grounded capacitors and four resistors through an analytical synthesis method is presented. The synthesis structure of the VM biquadratic filter consists of a voltage proportional block and two voltage lossless integrators based on the use of current feedback operational amplifiers (CFOAs). It is demonstrated that the derived biquadratic filter structure can simultaneously realize VM HPF, BPF and ILPF transfer functions or VM BPF and LPF transfer functions at a high-input impedance terminal. The VM biquadratic filter can independently adjust the resonance angular frequency and quality factor. By slightly modifying the proposed biquadratic filter, a VM quadrature sinusoidal oscillator can be achieved. The proposed biquadratic filter and quadrature oscillator have been simulated by OrCAD PSpice and appropriate hardware has been implemented with AD844-type CFOAs. In order to reduce power consumption, reduce chip area, reduce costs, and improve system integration, integrated VM CFOA-based biquadratic filter circuits and quadrature oscillator circuits are very important. The proposed filter and quadrature oscillator have been further fabricated in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.18~\mu \text{m}$ </tex-math></inline-formula> 1P6M CMOS process technology. The entire chip area is 0.974 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including a filter chip cell and an oscillator chip cell. Under the supply voltage of ±0.9 V, the total power dissipation of the filter chip cell is 5.4 mW, and the figure-of-merit (FOM) of filter chip cell is 66.7%. The measured value of the third-order intermodulation distortion of the filter chip cell is −55.29 dBc and the third-order intercept point is 19.9 dBm. The measured phase noise of CFOA-based filter chip cell at 1 kHz offset is less than −99.76 dBc/Hz.
Highlights
Due to the flexibility and versatility of active filters [1]–[7] and oscillators [8]–[14] in practical applications, people are increasingly interested in their design
This study developed a method of realizing VM multifunction biquadratic filter structure based on three current feedback operational amplifiers (CFOAs), two grounded capacitors and four resistors
The proposed VM biquadratic filter and oscillator were fabricated with Taiwan Semiconductor Manufacturing Company (TSMC) 0.18 μm CMOS 1P6M process technology
Summary
Due to the flexibility and versatility of active filters [1]–[7] and oscillators [8]–[14] in practical applications, people are increasingly interested in their design. The proposed circuit simultaneously realizes VM non-inverting high-pass filter (HPF), band-pass filter (BPF) and inverting low-pass filter (ILPF) transfer functions or VM BPF and non-inverting lowpass filter (LPF) transfer functions, employs two grounded capacitors attractive for integrated circuit (IC) technology implementation and able to absorb shunt parasitic capacitances, has high-input impedance suitable for cascading, and converts into a VM quadrature sinusoidal oscillator . An attractive feature of VM CFOA-based circuit with high-input impedance in this research is that the biquadratic ILPF, BPF and HPF transfer functions or the biquadratic BPF and LPF transfer functions can be simultaneously implemented on-chip. The first block diagram based on two-integrator loop VM multifunction biquadratic filter realizes HPF, BPF and ILPF transfer functions simultaneously. The second block diagram based on two-integrator loop voltage-mode biquadratic filter realizes BPF and LPF transfer functions simultaneously.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
