A novel DDCC+ based first-order current-mode active-C all-pass filter using a grounded capacitor

Abstract

In this study, a novel first-order current-mode active-C all-pass filter based on a companding idea is proposed. In the design of the filter, a state space method is used. The proposed structure consists of only two plus-type differential difference current conveyors, nine external MOSFETs, and a single grounded capacitor. The dominant advantages of the proposed filter are briefly described as follows: offering resistorless design, consuming low power, having an electronic tunability property of its pole frequency, and not suffering from the disadvantage of any passive component matching conditions. By cascading two all-pass filters in a closed negative feedback loop, a high-Q band-pass network is designed as an application example. Several simulations including frequency domain and time domain analyses by using the PSpice program are carried out to confirm the theoretical design. All the obtained simulation results are given and discussed.

An Analog CMOS Voltage-Controlled Phase-Shifter With A 100° Tuning Range For Telecommunication Baseband Signal Processing

“…Analog phase shifting circuits are mainly implemented as all-pass filters [4]- [10]. This family of filters exhibits a constant gain (usually 0 dB) over their whole operating frequency range and a phase, sometimes tunable via biasing voltage or current adjustment or passive component values modification.…”

“…First, some cannot be tuned [5]- [7]. When the circuit is tunable, the phase shift range is either limited [8], [9], or maximal at frequencies too low for baseband signal processing and phase HPA linearization [4], [10]. Further, tunability is often implemented through current biaising modifications of active blocks over several decades, which results in linearity issues [4], [5], [8].…”

“…In some cases, the architecture complexity may also prevent the use of these circuits in the context of HPA phase linearization [8], [11]. Nevertheless, architectures based on DDCC [9], [10], [12] show relatively good performances in terms of tuning range for an architecture rather simple to implement. However, none of them can be directly used because they do not meet the specifications mentioned above and because they do not include the implementation of a tunable passive component.…”

The development of a fully balanced current-tunable active-RC all-pass filter

“…In contrast, active filters operating in current mode offer the advantage of higher frequency capabilities compared to voltage mode filters. This is because current mode circuits have fewer internal nodes and exhibit enhanced accuracy when handling current signals [19][20][21].…”