FLEXIBLE DIFFERENTIAL FREQUENCY-TO-VOLTAGE AND VOLTAGE-TO-FREQUENCY CONVERTERS USING MONOLITHIC ANALOGUE RECONFIGURABLE DEVICES

This paper presents differential frequency-to-voltage (F/V) and voltage-to-frequency (V/F) converters employing single CMOS Field Programmable Analog Array (FPAA) device. The proposed electronic circuits are based on charge-balance conversion method. The F/V converter basically consists of analogue comparator, differentiator that detects the rising and falling edges of the shaped waveform, voltage-controlled switch and output low-pass filter, working as an averaging circuit. The V/F conversion circuit includes the same modules. The input signal for the V/F circuit is applied to an integrator (realized with low-pass filter) through two-position voltage-controlled switch and the positive feedback is closed by external electrical connections. The proposed converters can be redesigned during operation, in dependence on the amplitude, frequency range and noise level of the input signal, without using of external components or applying of external current or voltage. The functional elements of the converters are realized by employment of the available configurable analogue modules (CAMs) of the FPAA AN231E04 from Anadigm. The converters have wide-band frequency response and can operate with single supply voltage of 3.3V. The experimental results show that the linearity error is less than 0.5% at the frequency range of 0 to 20…25kHz and differential input range operation of 0 - 3V.