Quadraphonic Circuits
SM Quadrature Couplers have high performance, low cost - Application Note MiniCircuits.com (app note)
Surface Mount LTCC Quadrature Splitters - AN-10-005 Application Note MiniCircuits.com (app note)Surround Sound Decoder - This surround-sound decoder is based on the "Hafler" principle, first discovered by David Hafler sometime in the early 1970s. The original idea was to connect a pair of speakers
Two Quadrant Analog Multiplier uses No Log Amps - 10/10/96 EDN-Design Ideas: You usually obtain the product of two values by summing the outputs of logarithmic amplifiers. The block diagram in Figure 1 shows a configuration that produces a two-quadrant product of analog signals but uses no log amplifiers. VA and VB are the multiplier inputs. The triangle generator produces a linear triangle.2 Quadrant Analog Multiplier uses No Log Amps - 10/10/96 EDN-Design Ideas: You usually obtain product of two values by summing outputs of logarithmic amplifiers. block diagram in Figure 1 shows a configuration that produces a two-quadrant product of analog signals but uses no log amplifiers. VA and VB are multiplier inputs. triangle generator produces a linear triangle whose voltage range is between0V and maximum value that VB can attain (VB>=0V). VA may assume both positive and negative values. Figure 2 shows circuit waveforms.
Allpass Network shifts Signals 90° - 04/27/95 EDN-Design Ideas: Unlike low pass, band pass, and other magnitude-altering filters, allpass filters can shift the phase of a signal without affecting its amplitude.AN-10-005 Surface Mount LTCC Quadrature Splitters - Application Note MiniCircuits.com (app note)
AN-30-003 SM Quadrature Couplers have high Performance, Low cost - Application Note MiniCircuits.comAN-317: Circuit Applications of the AD7226 Quad CMOS DAC - AN-317 Analog Devices Application Notes
DDS forms inphase & quadrature generator - 12/04/97 EDN-Design Ideas: (design idea)Digital Delay Unit For Surround Sound - The Mitsubishi M65830 Digital Delay IC has been discontinued (for reasons beyond my comprehension), and so far a suitable replacement device has not been found. This means (of course) that you will be unable to build this delay circuit. I have left the project in place as reference, and the overall connection schematic is still valid if (when?) a replacement for the M65830 is located. The project will be updated at that time.