参数资料
| 型号： | IP-NCO |
| 厂商： | Altera |
| 文件页数： | 33/54页 |
| 文件大小： | 0K |
| 描述： | IP NCO COMPILER |
| 标准包装： | 1 |
| 系列： | * |
| 类型： | MegaCore |
| 功能： | 数控振荡器编译器 |
| 许可证： | 初始许可证 |
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4. Functional Description
Numerically Controlled Oscillators
A numerically controlled oscillator (NCO) synthesizes a discrete-time, discrete-valued
representation of a sinusoidal waveform.
There are many ways to synthesize a digital sinusoid. For example, a popular method
is to accumulate phase increments to generate an angular position on the unit circle
and then use the accumulated phase value to address a ROM look-up table that
performs the polar-to-cartesian transformation. You can reduce the ROM size by
using multipliers. Multipliers provide an exponential decrease in memory usage for a
given precision but require more logic.
Another method uses the coordinate rotation digital computer (CORDIC) algorithm
to determine, given a phase rotation, the sine and cosine values iteratively. The
CORDIC algorithm takes an accumulated phase value as input and then determines
the cartesian coordinates of that angle by a series of binary shifts and compares.
f For more information about the CORDIC algorithm, refer to A Survey of CORDIC
Algorithms for FPGAs by Andraka, Ray, FPGA ‘98 Proceedings of the ACM/SIGDA
Sixth International Symposium on Field Programmable Gate Arrays.
In all methods, the frequency at which the phase increment accumulates and the size
directly determines the normalized sinusoidal frequency. (Refer to the equation on
page 4–3 .)
When deciding which NCO implementation to use in programmable logic, you
should consider several parameters, including the spectral purity, frequency
resolution, performance, throughput, and required device resources. Often, you need
to consider the trade-offs between some or all of these parameters.
Spectral Purity
Typically, the spectral purity of an oscillator is measured by its signal-to-noise ratio
(SNR) and its spurious free dynamic range (SFDR).
The SNR of a digitally synthesized sinusoid is a ratio of the signal power relative to
the unavoidable quantization noise inherent in its discrete-valued representation.
SNR is a direct result of the finite precision with which NCO represents the output
sine and cosine waveforms. Increasing the output precision results in an increased
SNR.
The following equation estimates the SNR of a given sinusoid with output precision b :
SNR = 6 b – 1.8
? db ?
Each additional bit of output precision leads to an additional 6 dB in SNR.
November 2013
Altera Corporation
NCO MegaCore Function
User Guide
相关PDF资料 |
PDF描述 |
|---|---|
| IP-NIOS | IP NIOS II MEGACORE |
| IP-PCI/MT64 | IP PCI 64BIT MASTER/TARGET |
| IP-PCIE/8 | IP PCI EXPRESS, X8 |
| IP-POSPHY4 | IP POS-PHY L4 |
| IP-RIOPHY | IP RAPID I/O |
相关代理商/技术参数 |
参数描述 |
|---|---|
| IP-NIOS | 功能描述:开发软件 Nios II MegaCore RoHS:否 制造商:Atollic Inc. 产品:Compilers/Debuggers 用于:ARM7, ARM9, Cortex-A, Cortex-M, Cortex-R Processors |
| IPO-002-VSF-LF | 制造商:PROXISTOR AB ELECTRONIC 功能描述:PROXIMITY SWITCH, PNP; Sensor Input:Inductive; Sensing Range Max:2mm; Supply Voltage DC Min:10V; Supply Voltage DC Max:30V; SVHC:No SVHC (19-Dec-2012); External Depth:10.5mm; External Length / Height:16.5mm; External Width:30mm; |
| IPOD TOUCH4-C-B | 制造商:Distributed By MCM 功能描述:Apple® iPod Black Touch 4th Gen Digitizer + Glass 制造商:Distributed By MCM 功能描述:APPLE IPOD TOUCH DIGITIZER BLACK |
| IPOD TOUCH4-C-W | 制造商:Distributed By MCM 功能描述:APPLE IPOD TOUCH DIGITIZER WHITE 制造商:Distributed By MCM 功能描述:Apple® iPod White Touch 4th Gen Digitizer + Glass |
| IPP015N04N G | 功能描述:MOSFET OptiMOS 3 PWR TRANST 40V 120A RoHS:否 制造商:STMicroelectronics 晶体管极性:N-Channel 汲极/源极击穿电压:650 V 闸/源击穿电压:25 V 漏极连续电流:130 A 电阻汲极/源极 RDS（导通）:0.014 Ohms 配置:Single 最大工作温度: 安装风格:Through Hole 封装 / 箱体:Max247 封装:Tube |
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