Alan Li is a senior applications engineer with Analog Devices Inc., Norwood, Mass. He has a BSEE from Florida International University. Email address: Alan.Li@analog.com
3 results found for Alan Li, displaying items 1 - 3
April 27, 2006[Ideas For Design] Digital Volume Control Eliminates Zipper Noise
In low-end audio systems, digital potentiometers can be used as audio attenuators or amplifiers (Fig. 1). Unfortunately, a large change in volume at an arbitrary time can cause an abrupt discontinuity in the audio signal. The result is audible clicking, or zipper noise, which precludes the use of this simple design in mid-level or high-end audio systems. But designers can reduce zipper noise by converting the random change in...
April 28, 2005[Ideas For Design] Precision Programmable Current Sources Use Digital Pots
The circuit that's shown in Figure 1 implements a programmable 0- to 20-mA precision current source. The REF192 low-headroom 2.5-V voltage reference (U1) can source up to 30 mA. An AD5280 digital potentiometer (U2) controls the voltage-divider ratio of the reference voltage. U3, an OP1177 op amp, closes the loop by forcing VL = VW. At the digital pot's zero scale, where VWB ≈ 0 V, the voltage across RSET will approach zero and...
March 31, 2005[Ideas For Design] Precision Programmable Current Sources Use Digital Pots
The circuit shown in Figure 1 implements a programmable 0- to 20-mA precision current source. The REF192 low-headroom 2.5-V voltage reference (U1) can source up to 30 mA. An AD5280 digital potentiometer (U2) controls the voltage-divider ratio of the reference voltage. U3, an OP1177 op amp, closes the loop by forcing VL = VW...
