bucket-brigade device on:
[Wikipedia]
[Google]
[Amazon]
A bucket brigade or bucket-brigade device (BBD) is a 
The concept of the bucket-brigade device led to the
discrete-time
In mathematical dynamics, discrete time and continuous time are two alternative frameworks within which variables that evolve over time are modeled.
Discrete time
Discrete time views values of variables as occurring at distinct, separate "po ...
analogue delay line, developed in 1969 by F. Sangster and K. Teer of the Philips Research Labs in the Netherlands
)
, anthem = ( en, "William of Nassau")
, image_map =
, map_caption =
, subdivision_type = Sovereign state
, subdivision_name = Kingdom of the Netherlands
, established_title = Before independence
, established_date = Spanish Netherl ...
. It consists of a series of capacitance
Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are ...
sections C0 to Cn. The stored analogue signal is moved along the line of capacitor
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of ...
s, one step at each clock cycle
In electronics and especially synchronous digital circuits, a clock signal (historically also known as ''logic beat'') oscillates between a high and a low state and is used like a metronome to coordinate actions of digital circuits.
A clock sig ...
. The name comes from analogy with the term bucket brigade
A bucket brigade or human chain is a method for transporting items where items are passed from one (relatively stationary) person to the next.
The method was important in firefighting before the advent of hand-pumped fire engines, whereby fire ...
, used for a line of people passing buckets of water.
In most signal processing applications, bucket brigades have been replaced by devices that use digital signal processing
Digital signal processing (DSP) is the use of digital processing, such as by computers or more specialized digital signal processors, to perform a wide variety of signal processing operations. The digital signals processed in this manner are ...
, manipulating samples in digital form. Bucket brigades still see use in specialty applications, such as guitar effects.
A well-known integrated circuit
An integrated circuit or monolithic integrated circuit (also referred to as an IC, a chip, or a microchip) is a set of electronic circuits on one small flat piece (or "chip") of semiconductor material, usually silicon. Large numbers of tiny ...
device around 1976, the Reticon SAD-1024 implemented two 512-stage analog delay lines in a 16-pin DIP. It allowed clock frequencies ranging from 1.5 kHz to more than 1.5 MHz. The SAD-512 was a single delay line version. The Philips Semiconductors TDA1022 similarly offered a 512-stage delay line but with a clock rate range of 5–500 kHz. Other common BBD chips include the Panasonic MN3005, MN3007, MN3204 and MN3205, with the primary differences being the available delay time. An example of an effects unit utilizing Panasonic BBDs is the Yamaha E1010.
In 2009, the guitar effects pedal manufacturer Visual Sound recommissioned production of the Panasonic-designed MN3102 and MN3207 BBD chip that it offers for sale.{{Cite web, url = http://www.visualsound.net/index.php//resources/bbd_chips, title = Truetone, website = www.visualsound.net, access-date = 2016-06-17
Despite being analog in their representation of individual signal voltage samples, these devices are discrete in the time domain and thus are limited by the Nyquist–Shannon sampling theorem
The Nyquist–Shannon sampling theorem is a theorem in the field of signal processing which serves as a fundamental bridge between continuous-time signals and discrete-time signals. It establishes a sufficient condition for a sample rate that per ...
; both the input and output signals are generally low-pass filter
A low-pass filter is a filter that passes signals with a frequency lower than a selected cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency. The exact frequency response of the filter depends on the filt ...
ed. The input must be low-pass filtered to avoid aliasing
In signal processing and related disciplines, aliasing is an effect that causes different signals to become indistinguishable (or ''aliases'' of one another) when sampled. It also often refers to the distortion or artifact that results when ...
effects, while the output is low-pass filtered for reconstruction. (A low-pass is used as an approximation to the Whittaker–Shannon interpolation formula
The Whittaker–Shannon interpolation formula or sinc interpolation is a method to construct a continuous-time bandlimited function from a sequence of real numbers. The formula dates back to the works of E. Borel in 1898, and E. T. Whittaker i ...
.)
The concept of the bucket-brigade device led to the charge-coupled device
A charge-coupled device (CCD) is an integrated circuit containing an array of linked, or coupled, capacitors. Under the control of an external circuit, each capacitor can transfer its electric charge to a neighboring capacitor. CCD sensors are a ...
(CCD) developed by Bell Labs
Nokia Bell Labs, originally named Bell Telephone Laboratories (1925–1984),
then AT&T Bell Laboratories (1984–1996)
and Bell Labs Innovations (1996–2007),
is an American industrial research and scientific development company owned by mul ...
for use in digital cameras. The idea of using capacitors to retain a voltage state has older origins and separately led to Dynamic random-Access memory
Dynamic random-access memory (dynamic RAM or DRAM) is a type of random-access semiconductor memory that stores each bit of data in a memory cell, usually consisting of a tiny capacitor and a transistor, both typically based on metal-ox ...
where the charges are not propagated, but refreshed, in place.
See also
*Switched capacitor A switched capacitor (SC) is an electronic circuit that implements a function by moving charges into and out of capacitors when electronic switches are opened and closed. Usually, non-overlapping clock signals are used to control the switches, s ...
References