Patent Inventor: Russell J. Apfel

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Integrated circuit including a switching regulator design for power over Ethernet devices
Inventor: Apfel | Patent Number: 8064179

Methods and apparatus for low voltage control of a subscriber line interface circuit
Inventor: Apfel | Patent Number: 8019077

Output stacking architecture for an amplifier
Inventor: Apfel, et al. | Patent Number: 7970125

Power sourcing equipment device including a serial interface
Inventor: Apfel | Patent Number: 7960860

System and method of classification in power over ethernet systems
Inventor: Landry, et al. | Patent Number: 7793124

Voltage protection circuit for power supply device and method therefor
Inventor: Apfel | Patent Number: 7773354

Power supply with digital control loop
Inventor: Thompson, et al. | Patent Number: 7688119

System and method of classification in power over ethernet systems
Inventor: Landry, et al. | Patent Number: 7647510

Powered device including a detection signature resistor
Inventor: Landry, et al. | Patent Number: 7548799

Powered device including a classification signature resistor
Inventor: Landry, et al. | Patent Number: 7516340

System and method for high voltage protection of powered devices
Inventor: Apfel | Patent Number: 7511930

Current mirror architectures
Inventor: Apfel | Patent Number: 7477095

Current sensing echo cancellation device
Inventor: Apfel | Patent Number: 7215764

Method and apparatus for a single power supply for dual power mode
Inventor: Apfel | Patent Number: 7181002

Method and apparatus for a differential feedback in an active impedence feedback circuit
Inventor: Apfel | Patent Number: 7113590

Method and apparatus for phantom battery feed
Inventor: Apfel | Patent Number: 6956945

Method and apparatus for detecting and measuring foreign voltages
Inventor: Apfel, et al. | Patent Number: 6356624

Integrated ringer for short telephone lines
Inventor: Apfel | Patent Number: 6351528

Integrated ringer for short telephone lines
Inventor: Apfel | Patent Number: 6026159

Silicon controlled rectifier with reduced substrate current
Inventor: Apfel | Patent Number: 5986290

Integrated ringer for short telephone lines
Inventor: Apfel | Patent Number: 5694465

Variable DC feed characteristic in a subscriber line interface circuit
Inventor: Apfel | Patent Number: 5619567

Method and circuit for telephone dialing signal generation
Inventor: Misherghi, et al. | Patent Number: 4563548

Circuit with feedback for controlling the impedance thereof
Inventor: Apfel | Patent Number: 4359609

Current controlled battery feed circuit
Inventor: Apfel | Patent Number: 4315207

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