The following operators can be used to better focus your queries.
( ) , AND, OR, NOT, W/#
? single char wildcard, not at start
* multi char wildcard, not at start
(Cat? OR feline) AND NOT dog?
Cat? W/5 behavior
(Cat? OR feline) AND traits
Cat AND charact*
This guide provides a more detailed description of the syntax that is supported along with examples.
This search box also supports the look-up of an IP.com Digital Signature (also referred to as Fingerprint); enter the 72-, 48-, or 32-character code to retrieve details of the associated file or submission.
Concept Search - What can I type?
For a concept search, you can enter phrases, sentences, or full paragraphs in English. For example, copy and paste the abstract of a patent application or paragraphs from an article.
Concept search eliminates the need for complex Boolean syntax to inform retrieval. Our Semantic Gist engine uses advanced cognitive semantic analysis to extract the meaning of data. This reduces the chances of missing valuable information, that may result from traditional keyword searching.
This circuit converts the absolute value of an input voltage to a current. The circuit has many applications such as the input stage for a square-law circuit.
English (United States)
This text was extracted from a PDF file.
This is the abbreviated version, containing approximately
86% of the total text.
Page 1 of 1
Improved Absolute Value Voltage to Current Converter
This circuit converts the absolute value of an input voltage to a current. The
circuit has many applications such as the input stage for a square-law circuit.
Fig. 1 shows an absolute value circuit which is a typical example of the prior
art. When Vin is positive, the amplifier turns on PNP device Q2 in order to
maintain the input of the amplifier near ground. If the current gain of Q2 is high,
then the current through R, I = Vin/R, passes through Q2 to the output. For
negative inputs, Q1 is turned on (Q2 off) by the amplifier, and the current through
R, I = Vin/R, passes through Q1 and is reflected by the current mirror B to the
output. The circuit suffers from a potential lack of symmetry between positive
and negative input signals. The lack of symmetry is ca by the gain error of the
current mirror B which can also vary with the current level adding a nonlinearity
to the circuit.
The circuit of Fig. 2 eliminates the symmetry problem by eliminating the
current mirror. Amplifiers A1 and A2 are high gain amplifiers; Q2 and Q3 are
high current gain PNP transistors. For positive Vin, amplifier A2 maintains node B
at ground by turning Q4 on (Q3 off). The input voltage Vin is impressed across
R, and the current, I = Vin/R, flows through PNP Q4 to the output. For negative
Vin, Q2 turns on and Q3 turns on. Vin is impressed across resistor R and the
desired current, Vin/R, flows through Q2 to the output. (Note that mat...