ADAPTIVE TRANSLINEAR ANALOG SIGNAL PROCESSING A PROSPECTUS Eric J. McDonald, Koji Mensa Odame, and Bradley A. Minch School of Electrical and Computer Engineering Cornell University Ithaca, NY 14853-5401
[email protected] ABSTRACT are directly implementable as networks of MITES. We have devised a systematic method of transforming high- One common implementation of a MITE unit is shown level time-domain descriptions of linear and nonlinear adap- in Fig. 1. In this case, we operate a floating-gate PMOS tive signal-processing algorithms into compact, continuous- transistor in weak-inversion in addition to using a cascode time analog circuitry using basic units called multiple-input transistor to reduce the effects of the gate-to-drain capac- translinear elements (MITES). In this paper, we describe itance and channel-length modulation. The input voltages, the current state of the an and illustrate the method with an VI and V,, capacitively couple into the floating gate through unit-sized capacitors. The drain current of this device is example of an analog phase-locked loop (PLL). given by I = Isew(I’,+1’d/UT, 1. CIRCUIT SYNTHESIS METHODOLOGY where I, is a pre-exponential scaling current, w is the weight- The class of dyiamic translinear circuits [ 1-31 makes possi- ing cwfficient of the inputs (accounting for the body-effect 2.’ _.ble a promising approach to the structured design of analog and the capacitive voltage divider, Cunjt/Ctota,),and UT is ”. .‘ signal and information processing systems [4]. Such cir- the thermal voltage, kT/q. ’ cuits are capable of accurately realizing a wide range of lin- ear and nonlinear systems whose behavior can be described 2.