Electronically Tunable Current-Mode Quadrature Oscillator Derived from First-Order Allpass Filter

Some time back, Kircay reported an electronically-tunable current-mode square-root-domain first-order filter capable of realizing low-pass (LP), high-pass (HP) and all-pass (AP) filter functions. When simulated in SPICE, Kircay’s circuit has been found to exhibit DC offsets in case of LP and AP responses and incorrect transient response in case of HP response. In this paper, an improved circuit overcoming these difficulties/deficiencies has been suggested and its workability of the improved circuit as well as its capability in meeting the intended objectives has been demonstrated by SPICE simulation results.

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An Active-C Current-Mode Universal First-Order Filter and Oscillator

Journal of Circuits System and Computers ◽

10.1142/s0218126619502190 ◽

2019 ◽

Vol 28 (13) ◽

pp. 1950219 ◽

Cited By ~ 5

Author(s):

D. Agrawal ◽

S. Maheshwari

Keyword(s):

Transfer Functions ◽

Current Mode ◽

Cmos Technology ◽

Monte Carlo Analysis ◽

Passive Element ◽

First Order ◽

Order Filter ◽

Sinusoidal Oscillator ◽

High Output Impedance ◽

Electronically Tunable

This paper presents an electronically tunable current-mode first-order universal filter. The proposed circuit employs only a single Extra-X Current-Controlled Conveyor (EX-CCCII) and a single grounded capacitor, which is suitable for IC implementation. The circuit can realize three current transfer functions simultaneously, namely low-pass, high-pass and all-pass. The proposed circuit exhibits low-input and high-output impedance, which is suitable for cascading. The pole frequency of the filter can be electronically tuned, by varying the bias current of EX-CCCII. The nonidealities and parasitic effects on the circuit performance are investigated in detail. Also, the Monte Carlo analysis is done to show the effect of active and passive element mismatches on the pole frequency. An eight-phase current-mode sinusoidal oscillator and current-mode second-order filter are further realized using the proposed circuit. The functionality of the proposed circuits is verified through PSPICE simulations, using 0.25-[Formula: see text]m TSMC CMOS technology parameters.

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GROUNDED CAPACITOR CM-APS WITH HIGH OUTPUT IMPEDANCE

Journal of Circuits System and Computers ◽

10.1142/s0218126607003861 ◽

2007 ◽

Vol 16 (04) ◽

pp. 567-576 ◽

Cited By ~ 8

Author(s):

SUDHANSHU MAHESHWARI

Keyword(s):

Current Mode ◽

Bias Current ◽

Output Impedance ◽

Quadrature Oscillator ◽

Pspice Simulations ◽

First Order ◽

External Bias ◽

High Output Impedance ◽

High Output

This paper presents a new first order current mode all-pass section (CM-APS) with a grounded capacitor and employing a modified current controlled conveyor. The new circuit with high output impedance is ideal for current-mode cascading and is tunable through an external bias current. The proposed circuit is unique due to its features, not exhibited by any of the available works on the topic. An application of the circuit in realizing a quadrature oscillator is also given. The theory is validated through PSPICE simulations using real device transistors.

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