Patent ID: 6275078
Filing Date: 2001-08-14
Classification: H04L

Abstract:
A line driver circuit, comprising:a buffer including an adjustable current source and having a signal input and a signal output that provides a line driver output signal buffered from the signal input, the buffer further including a tuning input connected to the adjustable current source; anda tuning circuit, comprising:a first current source producing a first current;a second current source producing a second current;a current mirror having a fixed branch connected to receive the first current and an adjustable branch connected to receive the second current, the current mirror further having a control input connected to the adjustable branch and having an output; anda comparison circuit receiving the current mirror output for comparison to predetermined output voltage limits, the comparison circuit generating a control signal for application to the control input to maintain a voltage of the current mirror output within the predetermined output voltage limits and generating a tuning signal for application to the tuning input of the buffer to adjust operation of the adjustable current source to control an output impedance of the buffer.