A low-input resistance class AB CMOS current-conveyor

In the companion paper we show that GAD67-GFP+ (GFP+) inhibitory neurons located in the Nucleus of Roller of the mouse brain stem can be classified into two main groups (tonic and phasic) based on their firing patterns in responses to injected depolarizing current steps. In this study we examined the responses of GFP+ cells to fluctuating sinusoidal (“chirp”) current stimuli. Membrane impedance profiles in response to chirp stimulation showed that nearly all phasic cells exhibited subthreshold resonance, whereas the majority of tonic GFP+ cells were nonresonant. In general, subthreshold resonance was associated with a relatively fast passive membrane time constant and low input resistance. In response to suprathreshold chirp current stimulation at a holding potential just below spike threshold the majority of tonic GFP+ cells fired multiple action potentials per cycle at low input frequencies (<5 Hz) and either stopped firing or were not entrained by the chirp at higher input frequencies (= tonic low-pass cells). A smaller group of phasic GFP+ cells did not fire at low input frequency but were able to phase-lock 1:1 at intermediate chirp frequencies (= band-pass cells). Spike timing reliability was tested with repeated chirp stimuli and our results show that phasic cells were able to reliably fire when they phase-locked 1:1 over a relatively broad range of input frequencies. Most tonic low-pass cells showed low reliability and poor phase-locking ability. Computer modeling suggested that these different firing resonance properties among GFP+ cells are due to differences in passive and active membrane properties and spiking mechanisms. This heterogeneity of resonance properties might serve to selectively activate subgroups of interneurons.

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An improved CMOS class-AB current conveyor

Proceedings of the 44th IEEE 2001 Midwest Symposium on Circuits and Systems. MWSCAS 2001 (Cat. No.01CH37257) ◽

10.1109/mwscas.2001.986175 ◽

2002 ◽

Author(s):

B. Calvo ◽

S. Celma ◽

P.A. Martinez ◽

M.T. Sanz

Keyword(s):

Current Conveyor ◽

Class Ab

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An improved CMOS class AB first generation current conveyor

2008 Joint 6th International IEEE Northeast Workshop on Circuits and Systems and TAISA Conference ◽

10.1109/newcas.2008.4606336 ◽

2008 ◽

Author(s):

Mourad Fakhfakh ◽

Mourad Loulou ◽

Esteban Tlelo-Cuautle

Keyword(s):

First Generation ◽

Current Conveyor ◽

Class Ab

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FULLY PROGRAMMABLE UNIVERSAL FILTER WITH INDEPENDENT GAIN-ω0-Q CONTROL BASED ON NEW DIGITALLY PROGRAMMABLE CMOS CCII

Journal of Circuits System and Computers ◽

10.1142/s0218126609005411 ◽

2009 ◽

Vol 18 (05) ◽

pp. 875-897 ◽

Cited By ~ 25

Author(s):

TAREK M. HASSAN ◽

SOLIMAN A. MAHMOUD

Keyword(s):

Cmos Technology ◽

Code Word ◽

Current Conveyor ◽

Current Gain ◽

Current Conveyors ◽

High Current ◽

Universal Filter ◽

Output Stage ◽

Class Ab ◽

Digitally Programmable

A fully programmable second-order universal filter with independently controllable characteristics is presented in this paper. The proposed filter is based on a new ± 0.75 V second-generation current conveyor with digitally programmable current gain. The input stage of the current conveyor is realized using two complementary MOS differential pairs to ensure rail-to-rail operation. The output stage consists of a Class-AB CMOS push-pull network, which guarantees high current driving capability with a 47.2 μA standby current. The digital programmability of the current conveyor, based on transistor arrays and MOS switches, provides variable current gain using a digital code-word. Two approaches for implementing current conveyors with programmable current gain either greater or less than one are described. The fully programmable universal filter and the proposed digitally programmable current conveyor circuits are simulated using PSPICE with 0.25 μm CMOS technology from MOSIS.

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