High Gain Amplifier Circuits

Analog input circuit serves any microcontroller: 12/20/2001 EDN - Design Ideas / The simple ADC in Figure 1 is perfect for getting analog signals into a purely digital microcontroller. Using just five surface-mount parts, you can assemble it for less than 50 cents (1000), which is approximately half the cost of a single-chip-ADC approach in the same volume. Moreover, this design takes only one pin from the microcontroller to operate.

Circuit performs high-speed voltage-to-current, current-to-current conversion: 07/25/02 EDN Design Ideas - The circuit in Figure 1performs active voltage-to-current conversion or acts as a variable-gain current mirror with high precision and bandwidth. A typical application is testing high-speed ICs or other devices that have inputs designed to be driven from current-steering DACs to enable a modulated voltage source to control the devices.

LED driver delivers constant luminosity: 06/12/03 EDN Design Ideas The circuit in Figure 1 is similar in principle to that of a previous Design Idea (Reference 1) but offers improved, more reproducible performance. The output current is almost constant over an input-voltage range of 1.2 to 1.5V and is insensitive to variations of transistor gain. Transistors Q1 and Q2 form an astable flip-flop.

Network imitates thermocouples: 11/08/01 EDN Design Ideas Thermocouples find widespread use for temperature measurement in systems. During system design or testing, you must observe the system's response at different temperatures. However, it's inconvenient to heat a thermocouple every time you need to check a system's performance. You can use the simple trick of touching the thermocouple with a hot soldering iron, but this method provides only.

Positive feedback yields fast amplifier with precision dc offset: 04/01/04 EDN Design Ideas Some signal-processing applications require a high-speed, low-noise, dc-coupled amplifier that incorporates a precision dc-offset adjustment. Examples include oscilloscopes, in which the offset adjustment typically acts as a "position" control), ADC-input gain blocks, and scanning-ion-beam-microscopy deflection circuitry.

Transmitter accurately transfers voltage input: 05/15/03 EDN Design Ideas - When you connect remote sensors to a central process Controller, a simple, robust, and commonly used interface is the 4- to 20-mA loop. The advantages of this current loop include the simplicity of just two twisted wires that share both power and signal, the loop's high noise immunity in harsh environments, and the de facto loop standard within the process-control industry.

Voltage-to-current converter drives white LEDs: 06/27/02 EDN Design Ideas - You sometimes need to drive a white LED from one 1.5V battery. Unfortunately, the forward voltage of a white LED is 3 to 4V. So, you would need a dc/dc converter to drive the LED from one battery. Using the simple circuit in Figure 1, you can drive one white LED or two series-connected green LEDs, using only a few components.

Voltage-to-current converter makes a flexible current reference: 09/18/03 EDN Design Ideas -The voltage-to-current converter in Figure 1 can both source and sink current. The circuit is more flexible than some traditional current references that require different topologies for current sourcing and sinking. Also, you can easily adjust the value of the current reference by simply adjusting the circuit's input voltage.

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