DDR SDRAM is a stack of acronyms. Double Data Rate (DDR) Synchronous Dynamic Random Access Memory (SDRAM) is a common type of memory used as RAM for most every modern processor. First on the scene of this stack of acronyms was Dynamic Random-Access Memory (DRAM), introduced in the 1970s. A clock does not regulate DRAM. […]
Sigma Delta ADC vs. SAR vs. Pipeline: How to Choose
Assuming that you are familiar with the fundamental specifications of an ADC and what they mean, the next step is to know your entire signal chain well and then work to fit the ADC to the requirements. After carefully determining signal chain requirements, then select your ADC with the understanding that if the ADC is […]
What are diodes? A quick refresher
A diode is a passive component made with semiconductor materials (a chip) that conducts current flowing in one direction but does not conduct current flowing in the opposite direction. The symbol for a diode (to the right in Figure 1) looks something like an arrow pointing in the direction of the forward current. Current flows […]
Reducing ringing or reflections by controlling impedance lines
What is a controlled impedance line? For one thing, the term has to do with Printed Circuit Board (PCB) traces and layouts, which get more complex with higher frequency signals. Generally, you need not worry much about controlling impedance in traces unless you are working with signals at or above 50 MHz. However, most of […]
Parasitic capacitance, inductance, and displacement current
When two electrical conductors are physically close, carry a charge, and there’s a voltage potential between them, they create a virtual capacitor between them, even if the conductors are insulated. The virtual capacitor between them is known as parasitic or stray capacitance. This can happen anywhere but is most troublesome between traces on printed circuit […]
Amplifiers: What do rail-to-rail and single supply mean?
With respect to analog signals, a “rail” is a boundary that a signal has to work within. For a long time, operational amplifiers have required opposite but equal voltage supplies. If you see a dual-supply or dual-voltage op amp, it means that two supply voltages power the amplifier; the absolute supply voltage levels are the […]
How IBIS models help with signal analysis
An Input Output Buffer Information Specification (IBIS) model is a standard in the semiconductor industry for modeling semiconductor devices from a behavioral perspective, for both analog and digital perspectives. IBIS modeling enables engineers to describe detailed signal behavior in a circuit design without revealing proprietary information about the circuits (or the processes used to make […]
Choosing a reference voltage for an ADC
Analog-to-digital converters (ADCs) need a reference voltage (VREF) input in order to operate properly. ADCs convert analog inputs that can vary from zero volts on up to a maximum voltage level that is called the reference voltage. The reference voltage determines the ceiling of what the ADC can convert, and is essentially the yardstick against […]
Choosing a reference voltage for an ADC
Analog-to-digital converters (ADCs) need a reference voltage (VREF) input in order to operate properly. ADCs convert analog inputs that can vary from zero volts on up to a maximum voltage level that is called the reference voltage. The reference voltage determines the ceiling of what the ADC can convert, and is essentially the yardstick against […]
What’s the difference between an analog switch and digital switch ICs?
Analog switch integrated chips (ICs), then turned on, will conduct both analog and digital signals from the input pin to the output pin. Digital switches can only accept digital signals and duplicate the logic level on the input pin at the output pin. When the digital switch is turned off, it returns to a default […]
